Solar water heaters are well known and are presently marketed in a large variety of different forms. In one arrangement, the solar water heater comprises backing means and collector means which are assembled to constitute a container in which the water to be heated is presented to the rays of the sun and heated surfaces of the collector means.
The collector means includes a panel manufactured from a good heat conducting material such as stainless steel, galvanized iron or copper sheeting and is set up, in an operative position of the heater, to face the sun for maximum absorption of the heat energy and transmission of radiated energy from the sun. In some solar water heaters, the backing means is manufactured from the same material as the collector means and then seam welded to the collector means to provide the container.
It has been found that there is a tendency for the dissolved solids in the water to deposit out on the collector means which leads to a substantial reduction in the efficiency of the solar water heater. In areas where the dissolved solids content of the water is high, the solar water heater may have to be cleaned out, i.e., descaled, regularly at short intervals of time. In the case where the collector means and the backing means are welded together, the descaling operation necessitates the use of a suitable reactant, for instance, an acid solution. Not only in this not satisfactory in that the descaling is never complete over the entire inner area of the collector means, but pitting away of the container's metal surface occurs with obvious disadvantages. Furthermore, inspection of the container's interior is not possible to establish the degree of descaling achieved. Also, the container must be dismantled in order to effect descaling. Seen as a whole, therefore, such welded forms of containers are not satisfactory, particularly when regular descaling is necessary in areas where the water used has a high dissolved solids content.
In order to overcome these problems inherent in solar water heaters having a welded container as described above, it is known to provide a container in which the backing means and the collector means are bolted together, a suitable gasket being sandwiched between the collector means and backing means to establish the required liquid seal between these members. Loosening the bolts permits the backing means and the collector means to be separated for purposes of mechanically descaling and inspecting the interior of the container.
Generally, where the collector means is manufactured from a thin metal sheet as is usually the case, a large number of bolts must be used in order to maintain a good seal between the collector means and the backing means. It has been found that, not only is difficulty sometimes esperienced in unscrewing the bolts, for instance, due to rust or damage, but difficulty is also sometimes experienced in locating the bolts back in position during re-assembly of the container. Because of this and the large number of bolts involved, the operation of dismantling and re-assembling such container can, therefore, be time consuming.
An object of the present invention is the provision of a solar heat collector in which this difficulty is overcome to a large extent.